Field of the Disclosure
This disclosure relates to a liquid fluoropolymer coating composition and a fluoropolymer coated film.
Description of the Related Art
Films comprised of fluoropolymers, such as polyvinyl fluoride, ethylene/tetrafluoroethylene copolymers and perfluoropolymers (e.g., DuPont™ Teflon® FEP, DuPont™ Teflon® PFA, etc.), along with polytetrafluoroethylene coated fiberglass and silicone coated polyester are commonly used for release from composite materials such as printed circuit boards and aircraft interiors. Although they possess superior release properties, fluoropolymers have the disadvantage of being expensive. Polyester films are much cheaper, but do not possess the superior release properties of fluoropolymers and are themselves not suitable release films. A silicone coated polyester has better release properties than the polyester alone, but is known to transfer silicone to the composite material under some conditions, which can interfere with the functionality of the composite material, for example by leaving a siloxane layer on the composite affecting its adhesion properties. There exists a need for release films that combine the superior release properties of fluoropolymer film with the cost advantages of polyester film.
Liquid coating compositions can provide thin fluoropolymer films on polymeric substrate films. Examples of these systems are described in U.S. Pat. Nos. 7,553,540; 7,981,478; 8,012,542; 8,025,928; 8,048,513; 8,062,744; 8,168,297; and 8,197,933, and U.S. Patent Application Publication Nos. 2011/0086954 and 2012/0116016. Some of these systems include the use of primers on the polymeric substrate to be coated, while other systems disclose fluoropolymer coatings applied directly to unprimed polymeric substrates. In the case of using fluoropolymer coatings applied directly to unprimed polymeric substrates, it can be challenging to achieve sufficient adhesion of the fluoropolymer coating to the polymeric substrate.